The role of genetic factors in the between subject variation in the response to oral disease will be studied using the salivary peroxidase model. Genetically determined structural heterogeneity in peroxidase will be compared with differences in salivary antibacterial activity and dental caries scores in humans. Initial phases of the study will comprise establishment of reliable measures for easy detection of the structural variation in the enzyme and differences in antibacterial activity. Electrophoretic and chromatographic procedures will be used to modify existing methods such that easy typing of typed subjects and of those desgnated "no type" in earlier work will be possible. Existing measures of antibacterial activity will be adapted to allow tests to be made against micro-organisms of significance in dental caries. Both antibacterial activity and peroxidase structural typing will be correlated with dental caries in three types of subjects: 1) a large random non-related population, 2) members of families with at least 4 individuals available for testing; and 3) individuals having either very high caries (greater than 15 DMF) or low caries scores. All subjects will be faculty, students, staff or patients of the University of Connecticut Health Center who have had a thorough clinical and radiographic examination in the dental clinic. Caries scores will be recorded as DMFS or dmfs based on examination. A three-way analysis of variance will be used to test for correlations between these factors. This research is of significance in: 1) The study of the role genetic factors play in the response of the individual to dental caries. Salivary peroxidase is clearly not the only factor involved in this way but does provide a useful model for a study of this type. 2) The study of the relationship between a genetic polymorphism and the functional factors which might have maintained it in the population. 3) Providing a potential method by which the clinician might recognize through genetic typing the individual who is especially susceptible or resistant to dental caries.